Kirishima might not be first in the class but he's way smarter than to take Bakugou at his word about exactly what he's ready for during his next heat.

Kirishima's sure he's the Prince Charming of this story. Bakugou is not exactly the princess he's been expecting. (spoilers through the 90s of the manga)

On the way back to the mountains to get Kirishima some remedial dragon fire-breathing lessons, Bakugou agrees to let Kirishima scentmark him so the other dragons don't get any fresh ideas (if 'agrees to' means 'is completely into it').

Prompt from the Kink Meme: Kirishima gets oversensitive after using his quirk too much, and somebody (Bakugou) fucks him until he's so overstimulated that he cries

“I already told you, I’m not gonna break, you don’t have to go slow.” “What if I want to, though?” Kirishima murmurs quietly. “What if I wanna take my time with you?” Bakugou shivers.

Apparently bad things really did come in threes, Bakugou thought wryly, as the firefighter closed the distance between them. Tall, tan, and jacked as hell, he was a strong contender for the single hottest person Bakugou had ever seen in his life. He was covered in soot and sweat that contoured his ridiculous muscles, making them look even more defined, and his clinging black tank top didn’t do much to hide the rest of him, either. His strong cheekbones and jaw had smears of black on them too, and Bakugou had the absurd thought that he wanted to lick them clean. Bakugou didn’t think it was possible, but he felt himself turning even redder. He would barely have been able to talk to someone as attractive as him on a good day, and he was about to have to explain to him that he’d tried to burn down his fucking house because he was being petty on Twitter. Super.

Kirishima lived for these moments. Bakugou pressed back against his chest, thighs spread over Kirishima's own, hands sparking and popping over Kirishima's shoulder while the redhead worshipped Bakugou's body with his hands. ----- (Alternately summarized as: another fic where Bakugou can't jerk off but his bro helps and then feelings show up)

Kirishima hates his luck. Not only is he a stupid Alpha, but his longtime crush is also an Alpha, (Except he's knot) AND he's the only guy in the world that has his ...problem. The fic where Kirishima has two knots but Bakugou is up to the challenge.

“I-” He stuttered, trying to gather enough brainpower to talk. “M’sorry, I-I can’t-” And he really couldn’t, just couldn’t help himself from dropping back down on the dildo, couldn’t stop the filthy moan from leaving his mouth. He was so fucking turned on, and despite the fact that he might be in the process of ruining his friendship with the most important person in his life, he just couldn’t stop. Kiri’s eyes felt like fire on his skin and it was just dragging him higher, higher, higher. Bakugou likes to dress up. Kirishima catches him.